P0956: Auto Shift Manual Mode Circuit Range/Performance

What does P0956 mean?

The manual mode signal is electrically valid but contradicts other information, for example manual mode reported while the range sensor reads P, R or N, or the mode switch never changing although the up/down requests arrive. A Hyundai patent uses a microswitch with two opposing contacts and treats identical or missing signals on both inputs as a defect; a Nissan patent likewise compares two contacts of the manual mode switch. No manufacturer documents this exact code publicly, and Hyundai's mode circuit fault is only documented as the general code P0955. CARB requires rationality checks on such inputs. P0957 to P0959 cover low, high and intermittent faults. Manual mode is usually blocked.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Manual mode drops out or will not engage
• Display shows manual mode while lever is in D, or the reverse
• Warning lamp depending on manufacturer

Common causes

• High Mode switch or its actuating foot misaligned on the lever
• Medium Worn switch contacts giving contradictory states on both inputs
• Medium Transmission range sensor out of adjustment, disagrees with the mode signal
• Low Worn selector lever bushings allowing side play

Likelihood is a general estimate across vehicles; your make and model may differ.